1. Field of the Invention
The invention relates to out-of-ground cultivation techniques. More specifically, the invention relates to techniques in which the cultivation involves several successive stages of growth of seedlings, each stage leading to the use of a substrate offering a volume greater than that of the preceding one to make satisfactory development of the root system of the seedling possible.
2. Discussion of the Background
In intensive methods of out-of-ground cultivation, good management of materials and available space has lead to a series of stages being used corresponding to the use of specific substrates.
The most widely used method at the present time in out-of-ground cultivations in a greenhouse uses at least two successive stages. The first stage corresponds to the initial growth of the seedlings. Since the seedlings are not very bulky and exhibit a limited development of their root system, the professional at this stage preferably uses a substrate of limited volume. This makes it possible to multiply the number of seedlings cultivated in a limited space. It also makes it possible to minimize the volume of the nutritive solution necessary to maintain the substrate under conditions suitable for the development of the seedlings. In a second stage, the seedlings which have grown on these limited-volume substrates are placed, with the first substrate, on a second substrate offering a larger volume, and which are ordinarily spaced from one another.